GQFI-UGent-WST Seminar: Shota Komatsu 'Crosscap States in Integrable Field Theories and Spin Chains'

Crosscap states have been extensively studied in two-dimensional conformal field theory in the past, where part of the motivations came from their connection to orientifolds in string theory. Surprisingly however, analogous studies in (massive) integrable theories have been lacking. In this talk, Shota Komatsu (CERN) fills this gap by presenting a systematic study of crosscap states in integrable field theories and spin chains. First, Shota derives an exact formula for overlaps between the crosscap state and any excited state in integrable field theories with diagonal scattering. Using the formula, he computes the crosscap entropy i.e. the overlap with the ground state in several examples, and finds that it decreases monotonically along the renormalization group flow except in cases where the discrete symmetry is spontaneously broken in the infrared. He next introduces crosscap states in integrable spin chains and obtain exact determinant expressions for overlaps with energy eigenstates. These states are long-range entangled and provide interesting initial conditions for the quantum quench protocol, which are quite distinct from short-range entangled states corresponding to the boundary states. As a side result, Shota also briefly comments on the interplay between fermionization and Bethe ansatz.

This talk was recorded on February 8th, 2022 at the Albert Einstein Institute in Potsdam-Golm.